Make your own NES Game

I took an old Super Mario Brothers Nintendo video game and erased everything but the clouds. In section 1 is the source code with commentary, and in section 2 is a little tutorial on how to make your own version of this cartridge if you aren’t afraid of soldering irons.

Below I will go through the source code line by line. To compile this code you will need dasm and nbasic. nbasic is a small assembly wrapper for the Nintendo. The idea here is to simply write a program that will take the clouds from Mario Brothers and scroll them across the screen. Here comes the first line of code:
(beware, it’s assembly) :0

I was thinking that you could make a Super Mario Bros 4. This game has 2 villans: Wario and Waluigi. They both have started a company called the Super Wario Bros. They brainwashed Daisy, Luigi and Bowser Jr. You can play as Mario, Peach or Bowser with new power-ups like the star rod or the golden hammer.